Arth_4254 is a predicted 143 aa protein that exhibits 53% similarity across 132 aa of the C-terminal portion of the C. metallidurans ChrB1 protein. Together, Arth_4253 and Arth_4254 appear to encode the complete sequence for a full-length ChrB gene, but the gene sequences overlap by 4 nucleotides and a potential Shine-Dalgarno sequence is present upstream of the predicted start codon of Arth_4254. Repeated sequencing of this region did not reveal any potential sequencing errors that could explain this observation. Cell Cycle inhibitor RT-PCR analysis revealed that Arth_4253 and Arth_4254 can form a dicistronic

mRNA (operon structure analysis provided in Additional file 3). Arth_4249 contains 430 nucleotides, but AZD1480 purchase does not yield any hits to known genes at the nucleotide level. A BLASTx search of the translated nucleotide sequence versus the protein database shows that the predicted amino acid sequence is 76% similar to Arth_4254 across 77 aa. Arth_4252 encodes a 344 aa protein Luminespib containing a 40-residue YVTN family beta-propeller repeat

and a WD40 repeat domain (with 81% sequence similarity to ORF18 in Arthrobacter sp. strain CHR15) with an N-terminal signal sequence. The function of Arth_4252 is presently unknown, but other proteins within the WD40 repeat domain family are associated with the regulation of signal transduction and sensing membrane stress [28, 29]. Arth_4252 also shares 62% sequence similarity to Rmet_6194, which is located approximately Meloxicam 4 kb downstream of the C. metallidurans chrA1 gene, Rmet_6202. However, a functional role for Rmet_6194 in chromate resistance in this organism has not been established. Orthologs of Arth_4252 were also found in close proximity to chrA genes in Arthrobacter sp. strain CHR15 and several species of Burkholderia as revealed by a gene ortholog neighborhood search in the Integrated Microbial Genomes

database http://​img.​jgi.​doe.​gov. Arth_4247 has an expected protein sequence of 337 aa with a putative overlapping signal sequence and transmembrane helix at the N-terminus, which suggests that it is a membrane-anchored protein. The protein sequence shares 75% aa similarity with lipoproteins of the LppY/LpqO family, which were first described in Mycobacterium tuberculosis but have not been functionally characterized. Other mycobacterial lipoproteins have been shown to perform such diverse roles as binding solutes in ABC transporter complexes, sensing environmental stressors and participating in signal transduction mechanisms [30]. M. tuberculosis, like strain FB24, is a high GC% Gram positive bacterium of the order Actinomycetales. The role of lipoproteins in the response to Cr(VI) has not been established in other organisms. Other lipoproteins have been shown to participate in the response to divalent metals such as copper and lead [31, 32]. In the case of copper, NlpE stimulated the CpxAR envelope stress response pathway in copper-exposed E.